Robert Preston sparked concern in tonight's Coronation Street when girlfriend Michelle Connor accidentally revealed bruising on her arm, and he was later revealed to be taking steroids.

A worried Carla Connor turned detective when she noticed purple marks on dainty Michelle's arm and asked her where the bruises had come from.

Michelle, played by Kym Marsh, explained to best pal that the marks occurred during a moment of passion between them, but feisty Carla played by Alison King wasn't buying it.

She said: "There's passion and then there's knocking seven bells out of someone."

The bruises on Michelle's arm (Image: ITV/Coronation Street)

Robert, played by Tristan Gemmill, got the fitness bug while taking part in a charity boxing match in memory of mechanic Luke Britton.

The chef and bistro owner, who had surgery for testicular cancer last year, enjoyed fighting and said he was considering taking it up as a hobby.

Robert has been taking steroids (Image: ITV/Coronation Street)

After seeing Michelle's bruises a suspicious Carla was watching Robert closely, and he acted angry and aggressively towards her after she spotted him on the phone and later pocketing steroids from a dealer he met on the cobbles.

He rudely snapped at her to mind her own business but unable to let it lie she grabbed the stash from him.